Process of refining lead and zinc fume.



u 715,238. Paiehted Dec. 9, I902.

. r. L. BARTLETT. PRBCESS OF BEFINING LEAD AND ZiNC FUME.

(Application filed Mat. 25. 1901.]

(No Model.)

F% C\\\ f .more eminently fitted for painters use than FRANK L.BARTLETT, OF OANON CI PATENT OFFICE.

TY, COLORADO, ASSIGNOR TO THE UNITED STATES SMELTING COMPANY, ACORPORATION OF COLO- RADO.

PROCESS OF REFINING LEAD AND ZINC FUME.

SPECIFICATION forming part of Letters Patent No. 71 5,238, datedDecember 9, 1902.

Application filed March 25, 1901. Serial lit. 52,696- (No specimens.)

To all whom, it rmty concern:

Be it known that I, FRANK L. BARTLETT, a citizen of the United States ofAmerica, and a resident of Canon City, Fremont county, State ofColorado, have invented certain new and useful Improvements in Processesof Refining Lead and Zinc Fume, of which the following is aspecification.

My invention relates to the process of refining smelter-fume, such as isdescribed in my United States Patent No. 406,868, dated July 16, 1889.

The process of refining as set forth in the above-named patent consistedof passing the raw fume through externally-heated pipes in the presenceof air or of sulfurous-acid gas and continually stirring and scrapingthe fume from the walls of the retort during its passage through thesame. The effect of this process was to remove the carbonaceous matter,reduce the sulfates and sulfids, and to volatilize the arsenic and othervolatile impurities, leaving pure zinc and lead in the form of stablecompounds suitable for a white pigment. In practical operation theprocesses described gave satisfactory results and produced a pigmentapproaching white lead in color, weight, and consistency. I havediscovered since making application for the above-named patent that amore perfect pigment can be produced and that the color and body may beimproved by refining the raw fume in ovens or retorts, arranged so as toallow the products of combustion from carbonaceous fuel, andparticularly from a very smoky lignite or bituminous coal, to pass overand into the exposed fume while the same is being stirred. Further, thatby drawing out the fume while in a highly-heated condition into suitablereceptacles, preferably into iron boxes, and allowing it to stand forsome time it becomes very white, fine, and soft and is pigment refinedby my former processes. The

raw pigment is a mixture of zinc oxid, zinc sulfate and sulfite, leadoxid, sulfite, sulfid, V and sulfate, together with some carbon,arsonic, antimony, cadmium, and other elements.

- According to my process, as I put it into practical use, I expose theraw fume on the hearth of a furnace, over which the products ofcombustion of pure lignite are passed together with a proper amount ofair. The sulfites and sulfids are rapidly reduced to the oxide, thecarbonaceous matter is burned out, the volatile matter readily driven01f, and the lead oxid is to some extent converted into a carbonate, dueto the absorption of carbonic dioxid from the products of combustion.The process is extremely rapid, and when the color becomes a lightyellow the pigment is at once drawn out into iron boxes, where it isallowed to remain at a low heat for about four hours. In this conditionitabsorbs some oxygen, softens, and becomes well fitted for purposes forwhich it is designed. The amount of air and of smoky flame which isadmitted to the hearth is regulated by the operator by means ofproperlyconstructed dampers-as, for instance, if the nace especiallydesigned to carry out this 7 process.

In the drawings, Figure 1 represents a vertical section of the furnaceou the line 1 y of Fig. 2, the flue above the furnace being shown inelevation. Fig. 2 is a section on a; a: of Fig. 1, and Fig. 3 is anelevation of the same.

or represents the flat hearth of the furnace, generally rectangular inshape, and Z is the top or arch. The fume is put in through the twodoors f f, located at the end of the furnace, one at each side of thecenter, and it is withdrawn through a central discharge-opening 9 at theother end of the furnace. The

grates c 0, two in number, are at the corners at the discharge end andare below the level of the hearth a, with which they connect by means ofvertical fiues. Low bridge-walls 17 separate these fines from thehearth, these bridge-walls extending diagonally from the front to theside of the furnace.

j represents the furnace or firing door, and h is the ash-pit door. Theproducts of combustion pass out through a flue d in the top of thefurnace near the feed end, thence into a hood (1, and through the stack,in which is a damper m, by which the admission of air to the furnace andthe character of the flame are governed. In order to avoid the escape offume to the stack, a V-shaped protectingwall is built between thefeed-doors ff, extending to the top of the furnace at the inner end andnearly to the top directly beneath the opening d, so that the productsof combustion pass in at the sides and then up, thus forming acircuitous passage to the stack. The fume is received as it comes fromthe furnace in an iron box or car it, and over the discharge-door is aVentilating-hood n for the purpose of carrying off the gases andpreventing their escape in the room.

In operating I charge the raw fume into the doorsf and push it forwardin a mass until exposed to a low heat, banking the doors with the fumeto prevent influx of cold air at the charging-doors. Fire is started inthe fire-boxes and the furnace brought up to a low red heat, admissionof air being regulated under the grates and the damper in the chimneyconnection. By checking the draft into the chimney a very smoky flamecan be made to fill the entire furnace or even to deposit soot in thefurnace or by opening the chimney-damper and allowing more air to passthe grates the flame can be changed at once to a clean smokeless heat.When the pile of fume in the rear is brought up toa low red heat, theoperator begins to draw it forward toward the front of the hearth,constantly stirring and working the fume. As it reaches the front of thefurnace it is subjected to the action of a clean flame heavily chargedwithcarbonic dioxid, and it is subjected to this flame with continualstirring until the fume flashes out to a clean-white or yellowish-whitecolor, when it is ready to discharge into the iron box K, the hood nover the box being for the purpose of drawing off the dust and productsof combustion away from the operator. At regular periods a fresh chargeis pushed forward from the feed-doors, and the operator in frontconstantly draws the charges when in his opinion they are suitablyrefined, making the operation continuous. An important feature of theprocess is to draw the hot fume rapidly into the box K in order to keepit hot until filled. As soon as itis filled it is drawn to one side andallowed to stand about four hours. It retains a low red heat and thereactions continue in the box, particularly the reduction of the leadoxid to carbonate by the absorption of carbonic dioxid entangled withthe loose fume, cooling very gradually and absorbing oxygen as it cools.At the end of four or five hours the material has cooled enough so thatthe reactions cease, the top layer of about two inches is skimmed off,as it is somewhat discolored, and returned to the next refiningoperation in the ovens along with the raw fume. After skimming thebalance in the box is found to be well refined and of an exceptionallyfine white texture and is then ready for the market.

The expression a collected mass or body of fume as used in the claims isintended to mean a body of fume which is subjected to treatment on thehearth of the furnace as distinguished from fume which is subjected totreatment while floating in a current of air or products of combustion.

I claim- 1. The herein-described process of refining zinc and lead fumewhich consists in subjecting a collected mass or body of the fume to theaction of heated carbonic-dioxid gas.

2. The herein-described process of refining zinc and lead fume whichconsists in subjecting a collected mass or body of the fume to theaction of the products of combustion of carbonaceous fuel.

3. The herein-described processof refining zinc and lead fume whichconsists in subjecting a collected mass or body of the fume to theaction of the products of combustion of carbonaceous fuel and stirringit while subjected to such action.

4. The herein-described process of refining zinc and lead fume whichconsists in subject ing a collected mass or body of the fume at a lowred heat to the action of the products of combustion of carbonaceousfuel.

5. The herein-described process of refining zinc and lead fume whichconsists in subjecting a collected mass or body of the fume to theaction of a smoky flame.

6. The herein-described process of refining zinc and lead fume whichconsists in subjecting a collected mass or body of the fume at a low redheat to the action of a smoky flame.

7. The herein-described process of refining zinc and lead fume whichconsists of subjecting the collected mass or body of the fume to theaction of a smoky flame and then to the action of carbonic dioxid.

8. The herein-described process of refining zinc and lead fume whichconsists of subjecting the collected mass or body of the fume to theaction of a smoky flame and then to the action of a smokeless flame.

9. The herein-described process of refining zinc and lead fume whichconsists in subjecting a collected mass or body of the fume at a low redheat to the action of the products of combustion of carbonaceous fuel,stirring the fume while subject to such action, withdrawing it from suchaction into a suitable receptacle and allowing it to slowly cool.

10. The herein-described process of refining zinc and lead fume whichconsists of subjecting a collected mass or body of the fume at a 10W redheat to the action of the products Signed at Portland, Maine, this 2dday of of combustiqn of ca 'bonaceons fuei, stiring March, 1901. thefume whlle SUbJGOt to such action, witn- FRANK L. BARTLETT.

drawing it from such action into a. suitable 5 receptacle, allowing ithe cool slowly and Witnesses:

finally separating the outer layer offnme S. W. BATES, from the body ofthe mass. L. M. GODFERY.

